The WORKHORSE M-LOK compatible rail system was designed to be a lightweight and slimline option to be used on MIL-SPEC carbines available on the market today. With MLOK mounting options at the 3, 6 and 9 o'clock positions and skeletonized areas where MLOK is not used. They maintain 1913 MIL-SPEC Picatinny rail at the 12 o'clock position that is "notch cut" to match their upper receiver and reduce weight again.